Electrophotographic plate and process comprising photoconductive charge transfer complexes



United States Patent ELECTROPHOTOGRAPHIC PLATE AND PROC- ESS COMPRISINGPHOTOCONDUCTIVE CHARGE TRANSFER COMPLEXES Joseph Mammino, Penfield,N.Y., assignor to Xerox Corporation, Rochester, N.Y., a corporation ofNew York No Drawing. Filed May 27, 1966, Ser. No. 553,325

19 Claims. (Cl. 96-15) ABSTRACT OF THE DISCLOSURE Photoconductivematerials are prepared from polyphenylene oxide resins and Lewis acids.The materials are charge transfer complexes. The photoconductivematerials are used to make electrophotographic plates. Methods of usingthe plates are also disclosed.

This invention relates to photoconductive materials, and moreparticularly, to their use in electrophotography.

It is known that images may be formed and developed on the surface ofcertain photoconductive materials by electrostatic means. The basicxerographic process, as taught by Carlson in U.S. Patent 2,297,691,involves uniformly charging a photoconductive insulating layer and thenexposing the layer to a light-and-shadow image which dissipates thecharge on the areas of the layer which are exposed to light. Theelectrostatic latent image formed on the layer corresponds to theconfiguration of the lightand-shadow image. This image is renderedvisible by depositing on the image layer a finely divided developingmaterial comprising an electroscopic marking material called a toner.The powder developing material will normally be attracted to thoseportions of the layer which retain a charge, thereby forming a powderimage corresponding to the latent electrostatic image. This powder imagemay be transferred to paper or other receiving surface. The paper thenwill bear the powder image which may subsequently be made permanent byheating or other suitable fixing means. The above general process isalso described in U.S. Patents 2,357,809; 2,891,011 and 3,079,342.

That various photoconductive insulating materials may be used in makingelectrophotographic plates is known. Suitable photoconductive insulatingmaterials such as anthracene, sulfur, selenium or mixtures thereof, havebeen disclosed by Carlson in U.S. Patent 2,297,691. These materialsgenerally have sensitivity in the blue or near ultra-violet range, andall but selenium have a further limitation of being only slightly lightsensitive. For this reason, selenium has been the most commerciallyaccepted material for use in'electrophotographic plates. Vitreousselenium however, while desirable in most aspects, suffers from seriouslimitations in that its spectral response is somewhat limited to theultraviolet, blue and green regions of the spectrum and the preparationof vitreous selenium plates requires costly and complex procedures, suchas vacuum evaporation. Also, selenium plates require the use of aseparate conductive substrate layer, preferably with an additionalbarrier layer deposited thereon before deposition of the selenuimphotoconductor. Because of these economic and commercial considerations,there have been many recent efforts towards developing photoconductiveinsulating materials other than selenium for use in electrophotographicplates.

It has been proposed that various two-component materials be used inphotoconductive insulating layers used in electrophotographic plates.For example, the use of inorganic photoconductive pigments dispersed insuitable binder materials to form photoconductive insulating layers isknown. It has further been demonstrated that organic photoconductivedyes and a wide variety of polycyclic compounds may be used togetherwith suitable resin materials to form photoconductive insulating layersuseful in binder-type plates. In each of these two systems, it isnecessary that at least one original component used to prepare thephotoconductive insulating layer be, itself, a photoconductive material.

In a third type plate, inherently photoconductive polymers are used;frequently in combination with sensitizing dyes or Lewis acids to formphotoconductive insulating layers. Again, in these plates at least onephotoconductive component is necessary in the formation of the layer.While the concept of sensitizing photoconductors is, itself,commercially useful, it does have the drawback of being limited to onlythose materials already having substantial photoconductivity.

The above discussed three types of known plates are further described inU.S. Patents 3,097,095; 3,113,022; 3,041,165; 3,126,281; 3,073,861;3,072,479; 2,999,750; Canadian Patent 644,167 and German Patent1,068,115.

The polymeric and binder-type organic photoconductor plates of the priorart generally have the inherent disadvantages of high cost ofmanufacture, brittleness, and poor adhesion to supporting substrates. Anumber of these photoconductive insulating layers have low temperaturedistortion properties which make them undesirable in an automaticelectrophotographic apparatus which often includes powerful lamps andthermal fusing devices which tend to heat the xerographic plate. Also,the choice of physical properties has been limited by the necessity ofusing only inherently photoconductive materials.

Inorganic pigment-binder plates are limited in usefulness because theyare often opaque and are thus limited to use in systems where lighttransmission is not required. Inorganic pigment-binder plates have thefurther disadvantage of being non-reusable due to high fatigue and roughsurfaces which make cleaning difficult. Still another disadvantage isthat the materials used have been limited to those having inherentphotoconductive insulating properties.

It is, therefore, an object of this invention to provide aphotoconductive insulating material suitable for use inelectrophotographic plates devoid of the above-noted disadvantages.

Another object of this invention is to provide an economical method forthe preparation of photoconductive insulating materials wherein none ofthe required components is by itself substantially photoconductive.

Another object of this invention is to provide a photoconductiveinsulating material suitable for use in electrophotographic plates inboth single use and reusable systerns.

Yet still another object is to provide a photoconductive insulatinglayer for an electrophotographic plate which is substantially resistantto abrasion and has a relatively high distortion temperature.

Yet, a further object of this invention is to providev anelectrophotographic plate having a wide range of useful physicalproperties.

A still further object of this invention is to provide photoconductiveinsulating layers which may be cast into self-supporting binder-freephotoconductive films and structures.

Still another object of this invention is to provide a novel combinationof initially non-photoconductive insulating materials suitable for usein the manufacture of the photoconductive insulating layer of axerographic plate which are easily coated on a desired substrate orcombined with a conductive layer.

Another object is to provide a transparent self-sup- 3 portingphotoconductive film adapted for xerographic imaging which does notrequire a conductive backing.

A still further object of this invention is to provide a photoconductiveinsulating material which may be made substantially transparent andwhich is particularly adapted for use in systems where lighttransmission is required.

The foregoing objects and others are accomplished in accordance withthis invention, generally speaking, by providing a photoconductivematerial adapted for use in electrophotographic plates which is obtainedby complexing:

(A) A suitable Lewis Acid with (B) A polyphenylene oxide resin havingthe general formula to 12 carbon atoms in X and Y; and n is a positiveinteger, at least 2.

It should be noted that neither of the above two components, (A) and (B)used to make the photoconductor of this invention is by itselfphotoconductive; rather, they are each non-photoconductive.

After the above substantially nonphotoconductive Lewis acid is mixed orotherwise complexed with said substantially nonphotoconductive resinousmaterial, a highly desirable photoconductive insulating material isobtained which may be either cast as a self-supporting layer or may bedeposited on a suitable supporting substrate. Any other suitable methodof preparing a photoconductive plate from the above photoconductivematerial may be used.

It has been found by the present invention that electron acceptorcomplexing may be used to render inherently nonphotoconductive electrondonor type insulators photoconductive. This greatly increases the rangeof useful materials for electrophotography.

A Lewis Acid is any electron acceptor relative to other materialspresent in the system. A Lewis Acid will tend to accept electronsfurnished by an electron donor (or Lewis base) in the process of forminga chemical compound or, in the present invention, a charge transfercomplex.

A Lewis Acid" is defined for the purposes of this invention as anyelectron accepting material relative to the polymer to which it iscomplexed.

A charge-transfer complex may be defined as a molecular complex betweensubstantially neutral electron donor and acceptor molecules,characterized by the fact that photoexcitation produces internalelectron transfer to yield a temporary excited state in which the donoris more positive and the acceptor more negative than in the groundstate.

It is believed that the donor-type insulating resins of the presentinvention are rendered photoconductive by the formation of chargetransfer complexes with electron acceptors or Lewis acids and that thesecomplexes, once formed, constitute the photoconductive elements of theplates.

Broadly speaking, charge transfer complexes are loose associationscontaining electron donors and acceptors, frequently in stoichiometricratios, which are characterized as follows:

(A) Donor-acceptor interaction is weak in the neutral ground state, i.e.neither donor nor acceptor is appreciably perturbed by the other in theabsence Of photoexcitation.

(B) Donor-acceptor interaction is relatively strong in the photo-excitedstate, i.e. the components are at least partially ionized byphotoexcitation.

(C) When the complex is formed, one or more new absorption bands appearin the near ultraviolet or visible region (wave lengths between3200-7500angstrom units) which are present in neither donor alone noracceptor alone, but which are instead a property of the donoracceptorcomplex.

Both the intrinsic absorption bands of the donor and the charge transferbands of the complex may beused to excite photoconductivity.

Photoconductive insulator for the purposes of this invention is definedwith reference to the practical application in electrophotographicimaging. It is generally considered that any insulator may be renderedphotoconductive through excitation by sufficiently intense radiation ofsufliciently short wave lengths. This statement applies generally toinorganic as well as to organic materials, including the inert binderresins used in binder plates, and the electron acceptor type activatorsand aromatic resins used in the present invention. However, the shortwave length radiation sensitivity is not useful in practical imagingsystems because sufliciently intense sources of wave lengths below 3200angstrom units are not available, because such radiation is damaging tothe human eye and because this radiation is absorbed by glass opticalsystems. Accordingly, for the purposes of this application, the termphotoconductive insulator includes only those materials which may becharacterized as follows:

1) They may be formed into continuous films which are capable ofretaining an electrostatic charge in the absence of actinic radiation.

(2) These films are sufliciently sensitive to illumination ofwavelengths longer than 3200 angstrom units to be discharged by at leastone half by a total flux of at most 10 quanta/cm. of absorbed radiation.

This definition excludes the resins and Lewis acids of our disclosurewhen used individually from the class of photoconductive insulators.

The polyphenylene oxide resins used in the present invention may beprepared in any conventional manner.

Any suita'ble polyphenylene oxide resin may be used in the presentinvention. Optimum sensitivity is obtained when using the resin obtainedby the copper catalyzed oxidation of 2,6-xylenol. This produces a resinhaving methyl groups at X and Y in the general formula given above. Foroptimum physical properties, a molecular weight in the region of 25,000to 30,000 is preferred. While 2,6-xylenol is preferred, any othersuitable phenol may be used to produce useful resins. Typical phenolsinclude phenol; 2-methyl phenol; 2-propyl phenol; 2- isobutyl phenol;2,6-diethyl phenol; 2,6-diisopropyl phenol; 2-ethyl-6-methyl phenol,etc.

Any suitable Lewis acid can be complexed with the above-notedpolyphenylene oxide resins to form the desired photoconductive material.While the mechanism of the complex chemical interaction involved in thepresent process is not completely understood, it is believed that acharge transfer complex is formed having absorption bandscharacteristics of neither of the two components consideredindividually. The mixture of the two nonphotoconductive components seemsto have a synergistic effect which is much greater than additive.

Best results are obtained when using these preferred Lewis acids:2,4,7-trinitro-9-fluorenone; tetrachlorophthalic anhydride,9-(dicyanomethylene) 2,4,7-trinitrofluorene; 2,3-dichloro 1,4naphthoq-uinone and mixtures thereof.

Other typical Lewis acids include quinones, such as pbenzo-quinone,2,S-dichlorobenzoquinone, 2,6 dichlorobenzoquinone, chloranil,naphthoquinone-( 1,4), 2-methlyanthraquinone,1,4-di-methyl-anthraquinone, l-chloroanthraquinone, anthraquinone 2carboxylic acid, 1,

S-dichloroanthraquinone, 1-chloro-4-nitro-anthraquinone,phenanthrenequinone, acenapthenequinone, pyranthrenequinone,chrysenequinone, thionaphthene quinone, anthraquinone-1,8 disulfonicacid and anthraquinone-Z- aldehyde, triphthaloyl-benzene-aldehydes suchas bromal, 4 nitrobenzaldehyde, 2,6 di chlorobenzaldehyde 2,ethoxy-l-naphthaldehyde, anthracene-9-aldehyde, pyrene- 3-aldehyde,oxindole-3-aldehyde, pyridine-2,6-dialdehyde, 'biphenyl-4aldehyde;organic phosphonic acids such as 4-chloro-3-nitro-benzene phosphonicacid; nitrophenols, such as 4-nitrophenol, and picric acid; acidanhydrides, for example, acetic-anhydride, succinic anhydride, maleicanhydride, phthalic anhydride, tetrachlorophthalic anhydride, perylene3,4,9,l tetracarboxylic acid and chrysene-2,3,8, 9-tetracarboxylicanhydride, di-bromo maleic acid anhydride; metal-halides of the metalsand metalloids of the Groups 1B, II through to Group VIII of thePeriodic System, for example: aluminum chloride, zinc chloride, ferricchloride, tin tetrachloride, (stannic chloride), arsenic trichloride,stannous chloride, antimony pentachloride, magnesium chloride, magnesiumbromide, calcium bromide, calcium iodide, strontium bromide, chromicbromide, manganous chloride, cobaltous chloride, cobaltic chloride,cupric bromide, ceric chloride, thorium chloride, arsenic triiodide;boron halide compounds for example: boron trifiuoride, and borontrichloride, and ketones, such as acetophenone benzophenone,2-acetyl-naphthalene, benzil, benzoin, S-benzoyl acenaphthene,biacene-dione, 9-acetyl-anthracene, 9-benzoyl-anthracene, 4-(4dimethylamino cinnamoyl). l-acetylbenzene, acetoacetic acid anilide,indandione-(1,3), (1,3- diketo-hydrindene,) acenaphthenequinone-dichloride, anisil, 2,2-pyridil and furil.

Additional Lewis acids are mineral acids such as the hydrogen halides,sulphuric acid and phosphoric acid; organic carboxylic acids, such asacetic acid and the substitution products thereof, monochloro-aceticacid, dichloroacetic acid, trichloro-acetic acid, phenylacetic acid, and6-methyl-coumarinylacetic acid(4); maleic acid, cinnamic acid, benzoicacid, 1-(4-diethyl-amino-benzoyl)- benzene-2-carboxylic acid, phthalicacid, and tetra-chlorophthalic acid,alpha-beta-dibromo-beta-formyl-acrylic acid (muco-bromic acid),dibromo-maleic acid, 2-bromobenzoic acid, gallic acid,3-nitro-2-hydroxyl-l-benzoic acid, 2-nitro phenoxy-acetic acid,2-nitro-benzoic acid, 3-nitro-benzoic acid, 4-nitro-benzoic acid,3-nitro-4- ethoxy-benzoic acid, 2-chloro-4-nitro-l-benzoic acid, 2-chloro-4-nitro-1-benzoic acid, 3-nitro-4-methoxy-benzoic acid, 4nitro-l-methyl benzoic acid, 2-chloro-5-nitrol-benzoic acid,3-chloro-6-nitro-l-benzoic acid, 4-chloro- 3-nitro-1-benzoic acid, 5chloro 3 nitro-Z-hydroxybenzoic acid, 4-chloro-2-hydroxy benzoic acid,2, 4- dinitro-l-benzoic acid, 2-bromo-5-nitro-benzoic acid, 4-chlorophenyl-acetic acid, 2-chloro-cinnamic acid, Z-cyanocinnamic acid,2,4-dichlorobenzoic acid, 3,5-dinitro-benzoic, 3,5-dinitro-salicylicacid, m'alonic acid, mucic acid, acetosalicyclic acid, benzilic acid,butane-tetracarboxylic acid, citric acid, cyanoacetic acid,cyclo-hexane-dicarboxylic acid, cyclo-hexenecarboxylic acid,9,l0-dich1orostearic acid, fumaric acid, itaconic acid, levulinic acid,(levulic acid), malic acid, succinic acid, alpha-bromostearic acid,citraconic acid, dibromo-succinic acid, pyrene-2,3,7,8-tetra-carboxylicacid, tartaric acid; organic sulphonic acids, such as 4-toluenesulphonic acid, and benzene sulphonic acid,2,4-dinitro-1-methyl-benzene-6- sulphonic acid, 2,6 dinitro-l-hydroxybenzene-4-sulphonic acid, 2-nitro-l-hydroxy-benzene-4-sulphonic acid, 4nitro 1 hydroxy-2-benzene-sulphonic acid, 3-nitro-2-methyl-l-hydroxy-benzene-S-sulphonic acid, 6 nitro-4-methyl-1-hydroxy-benzene-2-sulphonic acid, 4-chloro-1-hydroxy-benzene-3-sulphonic acid, 2-chloro 3 nitro-1-methyl-benzene-S-sulphonic acid and2-ch1oro-1-methylbenzene-4-sulphonic acid.

The following examples will further define the present invention. Partsand percentages are by weight unless otherwise indicated. The examplesbelow should 'be considered to illustrate various preferred embodimentsof the present invention.

In each example, the substance to be evaluated is coated from solutionby suitable means onto a conductive substrate and dried. The coatedplate is conected to ground and the layer is electrically charged in thedark by a corona discharge device (as described by Carlson in US. Patent2,588,699) to saturation potential using a needle-point scorotronpowered by a high voltage power supply manufactured by High Volt PowerSupply Company, Condenser Products Division, Model PS-l01M operating at7 kilovolts while maintaining the grid potential at 0.9 kilovolt using aKepco, Incorporated regulated D.C. supply (O-1500 volts). Charging timeis 15 seconds.

The electrostatic potential due to the charge is then measured with atransparent electrometer probe without touching the layer or affectingthe charge. The signal generated in the probe by the charged layer isamplified and fed into a Mosely Autograf recorder, Model 680. The graphdirectly plotted by the recorder indicates the magnitude of the chargeon the layer and rate of decay of the charge with time. After a periodof about 15 seconds, the layer is illuminated by shining light onto thelayer through the transparent probe using an American Optical Spencemicroscope illuminator having a G.E. 1493 medical type incandescent lampoperating at 2800 K. color temperature. The illumination level ismeasured with a Weston Illumination Meter, Model No. 756, and isrecorded in the table. The light discharge rate is measured for a periodof 15 seconds or until a steady residual potential is reached. Theillumination level in each example is about 57 foot-candles.

The numerical difference in the rate of discharge of the charge on thelayer with time in the light minus the rate of discharge of the chargeon the layer in the dark is considered to be a measure of the lightsensitivity of the layer.

A practical test is also made on each material under study which showsphotoconductivity. An electrophotographic image is produced by chargingthe material by corona discharge, exposing the material by projection toa light-and-shadow image and cascade developing the electrostatic latentimage by the method described by Walkup in US. Patent 2,618,551. Detailsof this Procedure are given in Example I.

Example I About 4 parts PPO PR5311, a polyphenylene oxide resin fromGeneral Electric, having the general formula:

i. a |n is dissolved in about 50 parts of dichlorobenzene. To thissolution is added a solution consisting of about 1 part2,4,7-trinitro-9-fiuorenone (Eastern Chemical Co.) dissolved in amixture of about 10 parts cyclohexanone and about 20 partsdichlorobenzene. The solution is coated to about 5 microns thicknessonto a 5 mil aluminum plate (type 1145-H19 sold by Aluminum Company ofAmerica) by flow coating. The coating is dried, then cured for about 30minutes at about C.

, A portion of this plate i negatively charged to about 250 volts bymeans of a corona discharge in the manner described by Carlson in US.Patent 2,588,699. The charged plate is then exposed for about 15 secondsby projection using a Simmons Omega D3 Enlarger equipped with a f4.5lens and a tungsten light source operating at 2950 K. color temperature.The light exposure is about 250 foot-candle-seconds. The plate is thencascade developed. The developed image is electrostatically trans ferredto a receiving sheet in the manner described by Schatfert in US. Patent2,576,047. The image on the receiving sheet corresponds to the originalprojected image. The plate is cleaned of residual toner and is reused asby the above-described process.

Another portion of the above plate is electrometered as previouslydescribed and the results are tabulated in the Table 1.

Example II A coating solution is prepared as described in Example Iabove, except that about 0.1 part of Brilliant Green Special Dye, atriphenyl methane type dye, Color Index No. 662, available from AlliedChemical Corporation, is added to the solution. The solution is appliedonto an aluminum plate as before and cured in an oven for about 30minutes at about 100 C.

The plate is charged, exposed, and developed as in Example I and theimage is fused onto the plate surface. The image developed on the platecorresponds to the original.

Another portion of the above plate is electrometered as previouslydescribed and the results tabulated in the table. As indicated in thetable, spectral sensitivity and photosensitivity of the plate isimproved by the addition of sensitizing dyes.

Example III A coating solution is prepared as described in Example Iexcept that the 2,4,7-trinitro fluorenone is not included. The solutionis applied onto an aluminum plate as before and cured in an oven forabout 30 minutes at about 100 C. The plate is charged, exposed anddeveloped as in Example I. No image is observed on the plate. Anotherportion of the plate is electrometered and the results are tabul'ated inthe table. As indicated by the table, the plate without the Lewis Acidhas no photosensitivity.

Example IV A coating solution is prepared as described in Example I,except that 9-(dicyanomethylene)-2,4,7-tinitrofluorene is used in placeof the 2,4,7-trinitrofluorenone. The solution is coated onto an aluminumplate as before and cured in an oven for about one hour at about 100 C.A portion of the plate is charged, exposed and developed as in ExampleI. A positive image of good quality results. Another portion of theplate is electrometered and the results listed in the table.

Example V A coating solution is prepared as in Example I above, exceptthat the 2,4,7-trinitro fluorenone is replaced with2,3-dichloro-1,4-naphthoquinone. The mixture is coated onto an aluminumsubstrate and cured. The plate is charged, exposed, and developed as inExample I above. A positive image of good quality i produced on thisplate.

Another portion of the above plate is electrometered as previouslydescribed and the results tabulated in the table.

Example VI About 2 parts of Lucite 2042, an ethyl methacrylate resinmanufactured by E. I. du Pont de Nemours and Company is dissolved inabout 10 parts of methyl ethyl ketone. The solution is applied onto analuminum plate to a thickness of about 5 microns and cured. The plate iselectrometered as described above and the results were tabulated.

This plate is used as a control. As indicated in the table, this resin,when used alone, has no photosensitivity.

Example VII About 0.2 part of 2,4,7-trinitrofluorenone is added to theresin coating solution prepared as described in Example VI above. Thissolution is applied onto an aluminum sheet to a thickness of about 5microns and dried. The plate is electrometered and the results aretabulated.

This plate indicates that the addition of a Lewis Acid to an inert resindoes not result in photosensitive response. This indicates that LewisAcids alone are not photosensitive.

Example VIII A plate is prepared as in Example VI, except that about 0.1part Brilliant Green Special dye is included. The plate iselectrometered as described above and the results listed in the table.This example shows that the sensitizing dye used in Example H is notitself photoconductive.

TABLE Initial Light Dark Residual Sensitivity Example potentialdischarge discharge potential (volts/ (volts) (volts/sec.) (volts/sec.)after 15 it.c.s.)

sec. (v.)

I +160 16.0 6.0 +00 17. 6 --300 64. 0 1. 8 70 109.1 II +205 8. 0 +60 197285 268 6. 6 -70 458 III +320 0 0 +320 0 -200 0 0 200 0 IV +440 50. 1 5.3 +215 78. 8 570 52. 0 4. 5 260 83. 3 V +360 8. 0 4. 0 +270 7. 2 -4l0 8.8 4.0 300 7. 7 VI 460 4. 4 4. 4 +390 0 500 5. 2 5. 2 4l0 0 VII +420 0 0+420 0 460 0 0 450 0 VIII +310 0 0 +310 0 330 0 0 330 0 In the abovetable, sensitivity represents the initial discharge rate uponillumination in volts/ 100 foot candle seconds corrected for the rate ofdark discharge. As shown by Examples I, II, IV and V, a mixture of apolyphenylene oxide resin and a Lewis acid is photoconductive. ExampleIII shows that a polyphenylene oxide resin used alone, with no Lewisacid, is not photoconductive. Example VIII indicates that a polysulfoneresin-Lewis acid complex can be dye sensitized. As shown by Example VI,Lucite 2042, is not photoconductive. Example VII shows that the Lewisacids used in Examples I, II, IV, V and VIII are not photoconductive inan inert Lucite binder.

Although specific materials and conditions were set forth in the aboveexamples, these were merely illustrative of the present invention.Various other compositions, such as the typical materials listed aboveand various conditions where suitable, may be substituted for thosegiven in the examples with similar results. The photoconductivecomposition of this invention may have other materials or colorantsmixed therewith to enhance, sensitize, synergize or otherwise modify thephotoconductive properties of the composition. The photoconductivecompositions of this invention, where suitable, may be used in otherimaging processes, such as those disclosed in copending applicationsSerial Nos. 384,737; 384,680 and 384,681, where their electricallyphotosensitive properties are beneficial.

Many other modifications of the present invention will occur to thoseskilled in the art upon a reading of this disclosure. These are intendedto be encompassed Within the spirit of this invention.

What is claimed is:

1. A photoconductive charge transfer complex material comprising amixture of a Lewis acid and a polyphenylene oxide resin having thegeneral formula:

I "-1 L I X and Y are each selected from the group consisting of H andalkyl radicals; the total number of carbon atoms in X and Y being up to12; and n is a positive integer, at least two, said photoconductivecharge transfer complex having at least one new absorption band within arange of from about 3200 to about 7500 angstrom units.

2. The photoconductive material of claim 1 wherein said polyphenyloneoxide resin has the formula:

l ll LQ. l.

wherein n is at least 50.

3. The photoconductive charge transfer complex material of claim 1comprising from about 1 to 100 parts by weight of resin for every onepart of said Lewis acid.

4. The photoconductive charge transfer complex material of claim 1wherein said Lewis acid is selected from the group consisting of2,4,7-trinitro-9-fiuorenone; tetrachlorophthalic anhydride;9-(dicyonomethylene)-2,4,7- trinitrofiuorene;2,3-dichloro-l,4-naphthoquinone; and mixtures thereof.

5. The charge transfer complex material of claim 1 wherein said Lewisacid comprises 2,4,7-trinitro-9-fluorenone.

6. A process for the preparation of a photoconductive charge transfercomplex material which comprises mixing a Lewis acid and a polyphenyleneoxide resin having the general formula:

i "1.1 LQ l wherein:

X and Y are each selected from the group consisting of H and alkylradicals; the total number of carbon atoms in X and Y being up to 12;and n is a positive integer, at least two, said charge transfer complexhaving at least one new absorption band within a range of from about3200 to about 7500 angstrom units.

7. The process of claim 4 wherein about 1 to about 100 parts by weightof resin are mixed with every one part of Lewis acid.

8. The process of claim 6 wherein said Lewis acid is selected from thegroup consisting of 2,4,7-trinitro-9- fiuorenone; tetrachlorophthalicanhydride; 9-(dicyonomethylene) -2,4,7-trinitrofluorene;2,3-dichloro-1,4-naphthoquinone; and mixtures thereof.

9. The process of claim 6 wherein said Lewis acid comprises2,4,7-trinitro-9-fiuorenone.

10. An electrophotographic plate comprising a support substrate havingfixed to the surface thereof a photoconductive charge transfer complexmaterial comprising a mixture of a Lewis acid and a polysulfone resincomprising recurring units having the formula:

1 ll LQJ.

X and Y are each selected from the group consisting of H and alkylradicals; the total number of carbon atoms in X and Y being up to 12;and n is a positive integer, at least two, said photoconductive chargetransfer complex having at least one new absorption band within a rangeof from about 3200 to about 7500 angstrom units.

11. The electrophotographic plate of claim 10 wherein said Lewis acid isselected from the group consisting of 2,4,7-trinitro-9-fiuorenone;tetrachlorophthalic anhydride;9-(dicyonomethylene)-2,4,7-trinitrofiuorene;2,3-dichlorol,4-naphthoquinone; and mixtures thereof.

12. The electrophotographic plate of claim 10 wherein said Lewis acidcomprises 2,4,7-trinitro-9-fluorenone.

13. The electrophotographic plate of claim 10 comprising from about 1 toabout 1 part of said resin for every one part of said Lewis acid.

14. A method of forming a latent electrostatic charge pattern comprisingcharging the electrophotographic plate of claim 10 and exposing saidplate to a pattern of activating electromagnetic radiation.

15. A method of forming a latent electrostatic pattern wherein the plateof claim 10 is electrostatically charged in an image pattern.

16. An electrophotographic process wherein the plate of claim 10 iselectrically charged, exposed to an image pattern to be reproduced, anddeveloped with electrically attractable marking particles.

17. An electrophotographic process wherein the plate of claim 10 iselectrostatically charged in an image pattern and developed withelectrically attractable marking particles.

18. The process of claim 16 further including the steps of transferringsaid marking particles to the surface of a receiving sheet, andrecharging, exposing and developing said plate to produce at least morethan one copy of the original.

19. The process of claim 17 further including the steps of transferringsaid marking particles to the surface of a receiving sheet, andrecharging, exposing and developing said plate to produce at least morethan one copy of the original.

References Cited UNITED STATES PATENTS NORMAN G. TORCHIN, PrimaryExaminer.

